1. Field of the Invention
The invention relates to a method of processing a digitized workpiece, particularly a three-dimensional model of a dental prosthetic item to be produced therefrom, by altering the surface data of the workpiece by means of a tool which acts on a local zone of action on the surface.
A design being processed by CAD is not constrained by the limitations of the physical characteristics of materials and tools, indeed, the operation of the tool can completely free itself from these characteristics and overcome their disadvantages. It is desired, in particular, to improve the operability thereof.
Existing dental CAD/CAM systems offer no free-form tools that go beyond the techniques used in conventional dental technology. Thus these free-form tools, like those used in manual processing of physical models, have the disadvantage that the fine structures of the surface are obliterated due to the application of wax.
2. Description of the Related Art
In dental CAD/CAM systems, various tools are used for designing models for the fabrication of dental prosthetic items. Using these tools, the digital model of the dental prosthetic item can typically be modified on a line or point basis. For example, the equatorial line can be changed, the whole model can be rescaled or displaced, individual cusps can be made higher or lower, or the site of a cusp point can be shifted.
Furthermore, tools are used with which one can freely change the shape of the surface and which are derived from techniques of conventional dental technology, for example, the application of drops of wax or the removal of material with a knife, both realized of course in a digital form.
The line-based or point-based tools are usually easy to use, but they have the disadvantage that the user can only insufficiently and indirectly influence the surface between the lines or points.
The tools derived from conventional dental technology are typically oriented toward the characteristics of mechanical tools like, for example, a knife, or toward the characteristics of wax, for example its drop size or its temperature.
It is an object of the invention to provide the user of CAD/CAM systems with a tool that gives him additional possibilities in designing the shape of models.